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authorLuo Meng <luomeng12@huawei.com>2020-10-23 14:20:05 +0800
committerJeff Layton <jlayton@kernel.org>2020-10-26 07:59:29 -0400
commit16238415eb9886328a89fe7a3cb0b88c7335fe16 (patch)
treec890e67a79e391ce51d8962b3dffd634ae61569b /fs/locks.c
parentLinux 5.10-rc1 (diff)
downloadlinux-dev-16238415eb9886328a89fe7a3cb0b88c7335fe16.tar.xz
linux-dev-16238415eb9886328a89fe7a3cb0b88c7335fe16.zip
locks: Fix UBSAN undefined behaviour in flock64_to_posix_lock
When the sum of fl->fl_start and l->l_len overflows, UBSAN shows the following warning: UBSAN: Undefined behaviour in fs/locks.c:482:29 signed integer overflow: 2 + 9223372036854775806 cannot be represented in type 'long long int' Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xe4/0x14e lib/dump_stack.c:118 ubsan_epilogue+0xe/0x81 lib/ubsan.c:161 handle_overflow+0x193/0x1e2 lib/ubsan.c:192 flock64_to_posix_lock fs/locks.c:482 [inline] flock_to_posix_lock+0x595/0x690 fs/locks.c:515 fcntl_setlk+0xf3/0xa90 fs/locks.c:2262 do_fcntl+0x456/0xf60 fs/fcntl.c:387 __do_sys_fcntl fs/fcntl.c:483 [inline] __se_sys_fcntl fs/fcntl.c:468 [inline] __x64_sys_fcntl+0x12d/0x180 fs/fcntl.c:468 do_syscall_64+0xc8/0x5a0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Fix it by parenthesizing 'l->l_len - 1'. Signed-off-by: Luo Meng <luomeng12@huawei.com> Signed-off-by: Jeff Layton <jlayton@kernel.org>
Diffstat (limited to 'fs/locks.c')
-rw-r--r--fs/locks.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/locks.c b/fs/locks.c
index 1f84a03601fe..bc08610bae2f 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -542,7 +542,7 @@ static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
if (l->l_len > 0) {
if (l->l_len - 1 > OFFSET_MAX - fl->fl_start)
return -EOVERFLOW;
- fl->fl_end = fl->fl_start + l->l_len - 1;
+ fl->fl_end = fl->fl_start + (l->l_len - 1);
} else if (l->l_len < 0) {
if (fl->fl_start + l->l_len < 0)